Content Mastery Tab has gone blank...

I opened up DS4.5 today and everything was fine. Somehow I clicked on the Content Library window and everything in it disappeared. Everything else seems to work fine, but the window is blank.and I can't get any of the icons to reappear. Is there anyway to reset the content library window?

Under the Actors, Wardrobe, & Props tab, there is the search bar and under that there is a bar that describes whats in the window below. Below that is the window pane which is blank. If I run a search, the pictures from the search show up, but I can't get the file list to show up or the categories.